Patent GB-471579-A (GB)
Title: Improvements in electric cooking apparatus
IPC: A47J37/08
Filed: 1936-09-08
Abstract: 471,579. Thermal switches. CHICAGO FLEXIBLE SHAFT CO. Sept. 8, 1936, No. 24497. Convention date, Sept. 10, 1935. [Class 38 (v)] [Also in Groups VI, XI, and XIII] An electric cooking-device having means for applying heat to articles to be cooked in succession, e.g. a bread toaster, includes a thermal element controlling the cooking intervals, and means for rapidly cooling the thermal element at the close of each cooking interval to condition it for the next cooking operation. A casing 31 is provided with slots 35 for the insertion of slices of bread, and with handles 36, 37, the latter being movable to operate the bread carrier. The casing is ventilated by slots 44 in the bottom. A knob 39 is provided for adjusting the degree of toasting. Toast carriers 96 are arranged between the heating elements and extend through slots 103 in the end plates 52, 53. The carrier is integral with a sliding member 104 which is actuated by the handle 37 to slide on vertical rods 106. A vertical lever 121 is carried bv a projecting lug 122 from the plate 52, and is engaged by a roller 123 carried by the sliding member 104. The lever 121 carries a cam 124 having an arm 126 spring-pressed against an abutment 127 on the lever. When the handle 37 is moved downward, the roller 123 engages the cam 124 so that the lever 121 actuates a lever 128 carrying contacts 129 to close the circuit of the heaters. The toasting period is controlled by a bimetallic strip 141 mounted on a member 132 having vertical ribs 137 and upward extensions 134, 135. One end of the strip 141 engages a spring strip 142. The strip carries an adjustable screw 144 attached to a spring 146 the opposite end of which is attached to a bell-crank lever 147. The opposite end 149 of the lever bears against a cam 151 actuated by a knob 39. Rotation of the knob 39 acts through the cam, bell-crank-lever and spring to vary the tension on the bimetallic strip 141, which is arranged to lie directly below the secondary heating element. A lever 155 is pivoted at 156 and is urged by a spring in a clockwise direction. One end 159 is adapted to be pressed down when the bimetallic strip seats against the top surface of the member 132, and the other end engages the lower end of the lever 121. When the handle 37 is pressed down to start the toasting operation, the contacts 129 are locked in the closed position by engagement of the lever 155 with lever 121. The bimetallic strip is heated by a secondary heating element and at a predetermined temperature, adjusted by the knob 39, snaps down against the upper surface of the member 132 thereby depressing the end 159 of the lever 155, raising the end 161 and releasing the lever 121 so that the current is cut off. The toasting period is varied by rotation of the knob 39 to vary the stress applied to the strip 141. Another bimetallic strip 164 carried an adjustable pin 165 which bears against the strip 142, so that at a predetermined temperature additional pressure is applied to the strip 141. The function of the strip 164 is to delay the action of the strip 141 in breaking the circuit if the apparatus is used for a second toasting operation immediately on the conclusion of the first operation, so that the strip 141 starts at a higher temperature. The toast is removed by manually raising the handle 37. When the strip 141 snaps on to the member 132, which is of aluminium, heat is rapidly lost, so that the strip returned to position for the next toasting operation. The member 132 is arranged over the openings 44 to facilitate cooling. Means such as a wire 168 may be provided so that the circuit is directly controlled by manually raising the member 104. If a single slice of bread only is toasted, the heat from the empty side of the toaster is reflected from baffle plates against the bimetallic strip, so that the toasting period is shortened by the requisite amount.